Well, with a p0430 you're looking at possibly the downstream O2 not functioning properly or a bad cat. If you don't have a misfire code, not running overly rich or overly lean, and the vehicle is generally running well, then your likely looking at one of those two options... For what it's worth, a complete Y-pipe assembly is around three hundred bucks with new cats. You can also just replace the faulty cat, but given the age of the vehicle the other is properly close on its heels.
I think you're talking about the passenger side tank on the radiator. If coolant is coming from the tank itself, or the seal between the aluminum core and plastic tank, then you'll likely need to have it repaired or replaced. I just recently had to replace the rad in my Burban, so I know that feeling. The gaskets that I referred to are the LIM gaskets, and are notorious for failures and internal/external coolant leaks. I wouldn't replace them unless they've already failed or you just want the peace of mind to know that it's done right, but if they're holding then leave them be.
It would really help to know the other code that is being set, as it may lead to a better solution. These engines are notorious for cap/rotor problems as well, so you may want to check, or likely replace them as well to prevent future issues.
I think you're talking about the passenger side tank on the radiator. If coolant is coming from the tank itself, or the seal between the aluminum core and plastic tank, then you'll likely need to have it repaired or replaced. I just recently had to replace the rad in my Burban, so I know that feeling. The gaskets that I referred to are the LIM gaskets, and are notorious for failures and internal/external coolant leaks. I wouldn't replace them unless they've already failed or you just want the peace of mind to know that it's done right, but if they're holding then leave them be.
It would really help to know the other code that is being set, as it may lead to a better solution. These engines are notorious for cap/rotor problems as well, so you may want to check, or likely replace them as well to prevent future issues.